The present invention relates generally to radio frequency (RF) communications systems, and more particularly, to a RF site communications link for transmitting and receiving signals or calls between centralized switching equipment of a RF communications system and at least one of a plurality of remote mobile communications RF base station sites.
FIG. 1 illustrates a schematic diagram of a simplified example of a RF communications system 100 having base stations 102 at multiple sites S1, S2 and S3 which provide communications to geographic areas A1, A2 and A3, respectively. The base stations 102 each include a radio repeater for receiving signals or calls from a mobile or portable transceiver 104 and retransmitting those signals to other mobile or portable transceivers 104 within the same geographic area served by the same site. If the transceiver 104 (unit 1) in area A1, for example, desires to communicate with another transceiver 104 in geographical area A2 served by base station site S2, the signal or call is transmitted from base station site S1 along communications link 106 to centralized switching equipment 108. The centralized switching equipment 108 then switches according to the signals received from base station site S1 to transmit the call on communications link 106' to the base station 102 at site S2 which receives the signal and transmits it to mobile transceiver 104 (unit 2) in area A2.
The communications links 106 and 106' may be either dedicated leased telephone lines and/or microwave transmission equipment which cause the system communications operator additional expenses in either leasing the dedicated telephone lines or the additional expense for the microwave transmission equipment and the licensing fees for the additional frequencies over which the microwave transmission equipment will operate.
RF leased line eliminator products, such as UNITEL-RTL100.TM. as manufactured by Telepoint Inc. or the like are available to provide point-to-point RF links to permit elimination of the leased telephone lines or microwave transmission equipment; however, these devices also use dedicated frequencies for the point-to-point links and require the system operator to obtain licenses for these additional frequencies.
It is accordingly a primary objective of the present invention to provide a novel RF communications link between a remote base station site and a central switch which permits elimination of the leased telephone lines and/or the microwave transmission equipment.
Other objects of the present invention, together with features and advantages thereof, will become apparent from the following detailed specification when read with the accompanying drawings in which like reference numerals refer to like elements.